| CAUTION | If Engine Control Module (ECM) replacement is instructed in following test, always ensure ECM electrical connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. |
Note. If DTCs P0110, P0115, P0120, P0450 and P1120 are output simultaneously, the E2 sensor ground circuit at terminal No. 18 (Green/White wire) at ECM electrical connector E7 may be open. See WIRING DIAGRAMS article. For ECM electrical connector terminal identification see scheme 4 It may be necessary to check Green/White wire between splice I4 and terminal No. 18 at ECM electrical connector E7. Splice I4 is located behind passenger's side of instrument panel. (Scheme 52)
Circuit Description
Intake Air Temperature (IAT) sensor is a thermistor built into Mass Airflow (MAF) meter and is used to monitor temperature of intake air flowing through MAF meter. DTC is set when ECM detects an open or short in IAT sensor circuit. If DTC P0110 exists, ECM will operate in fail-safe mode in which intake air temperature is assumed to be 68°F (20°C). Possible causes are
- IAT sensor circuit is open or shorted.
- Defective IAT sensor.
- Defective ECM.
Diagnostic Aids
After confirming DTC P0110, use Toyota hand-held tester or scan tool to access CURRENT DATA to read the intake air temperature for IAT sensor. If displayed intake air temperature is -40°F (-40°C), IAT sensor circuit may be open. If displayed intake air temperature is 284°F (140°C) or more, IAT sensor circuit may be shorted. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.
Scheme 52
- Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC) No. 3 at driver's side of instrument panel. see scheme 1 Turn ignition on and then turn hand-held tester or scan tool on.
- Using hand-held tester or scan tool, read intake air temperature for IAT sensor. If displayed intake air temperature is -40°F (-40°C), go to next step. If displayed intake air temperature is 284°F (140°C) or more, go to step 8. If displayed intake air temperature is the same as actual air intake temperature, problem is intermittent. Check for defective connections or intermittent problem in wiring between MAF meter and ECM. MAF meter is bolted to top side of air intake hose, near upper cap on air cleaner assembly and contains a Black 5-pin electrical connector. ECM is located behind glove box and heater duct. see scheme 2
- Turn ignition off. Disconnect electrical connector at MAF meter. MAF meter is bolted to top side of air intake hose, near upper cap on air cleaner assembly and contains a Black 5-pin electrical connector. Connect jumper wire between terminals No. 1 (Green/White wire) and No. 2 (Yellow/Green wire) on electrical connector for MAF meter. see scheme 5
- Turn ignition on. Using hand-held tester or scan tool, read intake air temperature for IAT sensor. If displayed intake air temperature is less than 284°F (140°C), go to next step. If displayed intake air temperature is 284°F (140°C) or more, check for defective electrical connections at MAF meter and electrical connector. If electrical connections are defective, repair as necessary. If electrical connections are okay, replace MAF meter. See «AIRFLOW METER»(ref-133227-S33806184422002021900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
- Turn ignition off. Remove jumper wire. Remove glove box and heater duct (if necessary) for access to ECM with electrical connectors still installed on ECM. see scheme 2 Ensure electrical connectors at ECM are securely installed so all terminals in electrical connectors are contacting terminals in ECM.
- Ensure electrical connector at MAF meter is still disconnected. Connect jumper wire between terminals No. 18 (Green/White wire) and No. 22 (Yellow/Green wire) at ECM electrical connector E7 with all electrical connectors installed on ECM. see scheme 4 This is the E2 and THA terminals on ECM.
- Turn ignition on. Using hand-held tester or scan tool, read intake air temperature for IAT sensor. If displayed intake air temperature is 284°F (140°C) or more, repair open Green/White wire or Yellow/Green wire between MAF meter and ECM. See «WIRING DIAGRAMS»(ref-133228) article. If displayed intake air temperature is not 284°F (140°C) or more, replace ECM.
- Turn ignition off. Disconnect electrical connector at MAF meter. MAF meter is bolted to top side of air intake hose, near upper cap on air cleaner assembly and contains a Black 5-pin electrical connector. Turn ignition on. Using hand-held tester or scan tool, read intake air temperature for IAT sensor. If displayed intake air temperature is not -40°F (-40°C), go to next step. If displayed intake air temperature is -40°F (-40°C), replace MAF meter. See «AIRFLOW METER»(ref-133227-S33806184422002021900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
- Turn ignition off. Remove glove box and heater duct (if necessary) for access to ECM with electrical connectors still installed on ECM. see scheme 2 Disconnect ECM electrical connector E7. see scheme 4 Ensure electrical connector is still disconnected at MAF meter.
- Turn ignition on. Using hand-held tester or scan tool, read intake air temperature for IAT sensor. If displayed intake air temperature is -40°F (-40°C), repair short in wiring harness and electrical connectors between MAF meter and ECM. See «WIRING DIAGRAMS»(ref-133228) article. If displayed intake air temperature is not -40°F (-40°C), replace ECM.